Robust data extension for 8vsb signaling

Abstract

A robust data extension is added to a standard 8VSB digital television transmission system by encoding high priority data packets in a rate 1/2 trellis encoder. The high priority data 1/2 trellis encoded packets are multiplexed with normal data packets and input into the normal data service of an 8VSB system, which further contains a rate 2/3 trellis encoder. The combined trellis encoding results in a rate 1/3 trellis encoding for robust data packets and a rite 2/3 trellis encoding for normal packets. Rate 1/3 trellis encoding provides the substantially equivalent robustness of a 2VSB signal while retaining the backward compatibility characteristics or an 8VSB signal. Four legacy requirements for backward compatibility with existing ATSC compliant receivers and transmitters are met: 1) the modulus of the symbol set for robust data transmission is the same as that for an 8VSB signal; 2) compatibility with existing trellis encoders and decoders is maintained; 3) Reed Solomon parity bytes are transmitted as normal data so that existing receivers do not flag robust data packets as having Reed Solomon parity errors; and 4) MPEG compatibility is maintained by guaranteeing that robust data packets will not appear as false MPEG packets that otherwise could destabilize the existing MPEG decoder.

What is claimed is:  
     
         1 . In a communications system responsive to first data, said communications system encoding said first data by a first encoding method, a method for transmitting second data over said communications system, said method comprising: 
 encoding said second data by a second encoding method to form encoded second data;    multiplexing said encoded second data with said first data to form multiplexed data; and    transmitting said multiplexed data over said communications system, whereby said first data is encoded by said first encoding method and said second data is encoded by said first encoding method and said second encoding method.    
     
     
         2 . A method in accordance with  claim 1 , wherein said first encoding method is rate 2/3 trellis encoding.  
     
     
         3 . A method in accordance with  claim 2 , wherein said second encoding method is rate 1/2 trellis encoding.  
     
     
         4 . A method in accordance with  claim 3 , wherein said communications system further includes integral pre-coding of data prior to said first encoding method, said method further comprising: 
 processing said second data by differentiating said second data so as to defeat said integral pre-coding of data when said encoded second data is transmitted over said communications system.    
     
     
         5 . A method in accordance with  claim 4 , further comprising the step of selectively inverting or not inverting said first data transmitted over said communications system to cancel phase errors generated by differentiating said second data.  
     
     
         6 . A method in accordance with  claim 1 , wherein said communications system further includes MPEG packets having an MPEG packet length, said method further comprising: 
 dividing said second data into second data packet lengths, each of said second data packet lengths being smaller than said MPEG packet length; and    attaching header bytes to each of said second data packets, each of said header bytes corresponding to a NULL packet header, said header bytes being encoded as said first data; and    encoding each of said second data packets as said second data.    
     
     
         7 . a method in accordance with  claim 1 , further comprising: 
 dividing said second data into a plurality of robust data packets;    computing Reed Solomon parity bytes for each of said plurality of robust data packets;    transmitting each of said Reed Solomon parity bytes for each of said plurality of robust data packets as said first data; and    transmitting each of said robust data packets as said second data.    
     
     
         8 . A method in accordance with  claim 1 , further comprising: 
 dividing said second data into a plurality of data packets;    computing Reed Solomon parity bytes for each of said plurality of data packets;    combining each of said Reed Solomon parity bytes with each respective ones of said plurality of data packets to form a respective plurality of robust data packets; and    transmitting each of said robust data packets as said second data.    
     
     
         9 . In a communications system responsive to first data, said communications system encoding said first data in a first encoder, an improvement for transmitting second data over said communications system, said improvement comprising: 
 a second encoder responsive to said second data to form encoded second data; and    a multiplexer responsive to said encoded second data and said first data to form multiplexed data; wherein 
 said transmitter is coupled to said multiplexer to'transmit said multiplexed data over said communications system,  
 whereby said first data is encoded by said first encoder and said second data is encoded by said first encoder and said second encoder.  
   
     
     
         10 . An apparatus in accordance with  claim 9 , wherein said first encoder is rate 2/3 trellis encoder.  
     
     
         11 . An apparatus in accordance with  claim 10 , wherein said second encoder is rate 1/2 trellis encoder.  
     
     
         12 . An apparatus in accordance with  claim 11 , wherein said communications system further includes an integral pre-coder prior to said first encoder, said apparatus further comprising: 
 a differentiator coupled to said second data so as to defeat said integral pre-coder when said encoded second data is transmitted over said communications system.    
     
     
         13 . An apparatus in accordance with  claim 12 , further comprising an invert/not invert for selectively inverting or not inverting said first data transmitted over said communications system.  
     
     
         14 . An apparatus in accordance with  claim 9 , wherein said communications system further includes MPEG packets having an MPEG packet length, said apparatus further comprising: 
 means for dividing said second data into second data packet lengths, each of said second data packet lengths being smaller than said MPEG packet length; and    means for attaching header bytes to each of said second data packets, each of said header bytes corresponding to a NULL packet header, said header bytes being encoded as said first data; and    means for encoding each of said second data packet lengths as said second data.    
     
     
         15 . An apparatus in accordance with  claim 9 , further comprising: 
 means for dividing said second data into a plurality of robust data packets;    means for computing Reed Solomon parity bytes for each of said plurality of robust data packets;    means for transmitting each of said Reed Solomon parity bytes for each of said plurality of robust data packets as said first data; and    means for transmitting each of said robust data packets as said second data.    
     
     
         16 . An apparatus in accordance with  claim 9 , further comprising: 
 means for dividing said second data into a plurality of data packets;    means for computing Reed Solomon parity bytes for each of said plurality of data packets;    means for combining each of said Reed Solomon parity bytes with each respective ones of said plurality of data packets to form a respective plurality of robust data packets; and    means for transmitting each of said robust data packets as said second data.